Skin and nail changes in the arthritic foot.

The arthritic process is unlikely to be confined to the foot; similarly the cutaneous lesions associated with the arthritic foot are often widespread. Careful examination of the skin and nails, particularly the finger nails, may be helpful in the differential diagnosis when the patient presents with a painful foot joint. Conversely, certain cutaneous lesions may alert the physician to the possibility of joint disorders presenting at some later date. In this chapter, it is not possible to mention every skin lesion associated with an arthropathy. Some skin lesions are specific but many are non-specific and occur in several rheumatic diseases. The rheumatologist and dermatologist work in closest co-operation when managing patients with lupus erythematosus and psoriatic arthritis and it is for this reason there is particular emphasis on these two diseases. Patients with rheumatoid arthritis and gout usually come within the province of the rheumatologist, but there are often many characteristic dermatological features to these diseases. This chapter also includes some more esoteric diseases such as Familial Mediterranean fever, Behçet's syndrome, disseminated gonococcal infection and Lyme disease which may present a diagnostic problem to the general physician, rheumatologist or dermatologist.